If δh = - 70.0 kj and δs = - 0.400 kj/k, the reaction is spontaneous below a certain temperature. calculate that temperature.

According to this formula, when:

ΔG = ΔH - T*ΔS

when the reaction is thermodynamically spontaneous ΔG < 0

∴ ΔH - T * ΔS = 0

∴T*ΔS = ΔH

∴ T = ΔH / ΔS

when we have:

ΔH = - 70KJ

and ΔS = - 0.4 KJ/K

So by substitution:

T = - 70KJ / - 0.4

= 175 K

∴the certain temperature below which the reaction will be thermodynamically spontaneous is 175 K